【導(dǎo)讀】對其的研究近幾年來倍受重視。傳統(tǒng)的安全策略如防火墻或VPN主要注重防護(hù)，而防。護(hù)相對進(jìn)攻來說總是滯后的。因為計算機系統(tǒng)和應(yīng)用軟件總是包含無法預(yù)知的漏洞，一。個時間差的必要手段。入侵檢測系統(tǒng)的主要特點是主動防御，即在入侵行為發(fā)生之前或。正在發(fā)生時就檢測出該行為。目前的入侵檢測方法主要分為兩類：誤用檢測和異常檢測?；诋惓５臋z測技術(shù)的優(yōu)點在于它能夠發(fā)現(xiàn)任何企圖發(fā)掘、試探系統(tǒng)漏洞的行為，但此方法的缺陷是較高的誤報率。本文首先綜述了網(wǎng)絡(luò)安全的攻擊和防御手段及當(dāng)前的研究現(xiàn)狀。之后又介紹了四種基于統(tǒng)計的異常檢測方法，他們分別。Web訪問的異常信息進(jìn)行檢測。目前，全球使用Inter的用戶已經(jīng)超過1億，并以更快速度增長。2020年中國將成為世界上擁。據(jù)通信網(wǎng)絡(luò)的安全受到危害，將會造成重大損失，引起社會混亂和危機國家安全。對數(shù)據(jù)的保護(hù)包括數(shù)據(jù)的機密性和完整性保護(hù)，主要針對數(shù)據(jù)竊取、數(shù)。及內(nèi)部合法用戶的超越使用權(quán)限的非法活動。

　　

【正文】 afford .,Zamboni detection using autonomous agents, Computer Networks,October 2020,34(4):547570 [33] Balasubramaniyan J.,GarciaFernandez .,Spafford .,Zamboni Architecture for Intrusion Detection using Autonomous of Computer Sciences,Purdue University。Coast TR 9805。1998. [34] Neumann :Event Monitoring Enabling Responses to Anomalous Live proceedings of National Information Systems Security Conference,October,1997. [35] Neumann .,Porras with EMERALD to First USENIX Workshop on Intrusion Detection and Network Clara, California,April,–80. [36] Stephanie F.,Hofmeyr ,Somayaji A,Longstaff sense of self for unix of the 1996 IEEE Symp on Security and Privacy,IEEE Computer Society Press,Los Alamitos,CA,1996:120128. [37] Hofmeyr S A,Forrest S,Somayaji detection using sequences of system of Computer Security,1998,6:151180 [38]Hofmeyr ,Forrest by design:an artificial immune : Proceedings of 1999 GECCO Conference,San Francisco,1999:12891296 [39] Li .,Huang Y.,Huang puting immune model based on poisson procedure and rough Journal of Computers,2020, :7176 (勵曉健，黃勇，黃厚寬基于 Poisson過程和 Rough包含的計算免疫模型。計算機學(xué)報，第26卷第 1期： 7176) [40] Ludovic :a Geic Algorithm as an Alternative Tool for Security Trails Analysis,in the Proceedings of First International Symposium of Recent Advances in Intrusion Detection,1998. Father, Mother, this is my friend, Professor Bhaer, she said, with a face and tone of such irrepressible pride and pleasure that she might as well have blown a trumpet and opened the door with a flourish. If the stranger had any doubts about his reception, they were set at rest in a minute by the cordial wele he received. Eve ryone greeted him kindly, for Jo39。s sa ke at first, but very soon they liked him for his own. They could not help it, for he carried the talisman that opens all hearts, and these simple people warmed to him at once, feeling even the more friendly because he was poor. For poverty enriches those who live above it, and is a sure passport to truly hospitable spirits. Mr. Bhaer sat looking about him with the air of a traveler who knocks at a strange door, and when it opens, finds himself at home. The children went to him like bees to a honeypot, and establishing themselves on each knee, proceeded to captivate him by rifling his poc kets, pulling his beard, and investigating his watch, w ith juvenile audacity. The women telegraphed their approval to one another, and Mr. March, feeling that he had got a kindred spirit, opened his choicest stores for his guest39。s benefit, while silent John listened and enjoyed the talk, but said not a word, and Mr. Laurence found it impossible to go to sleep. If Jo had not been otherwise engaged, Laurie39。s behavior would have amused her, for a faint twinge, not of jealousy, but something like suspicion, caused that gentleman to stand aloof at first, and observe the newer with brotherly circumspection. But it did not last long. He got interested in spite of himself, and before he knew it, was drawn into the circle. For Mr. Bhaer talked well in this genial atmosphe re, and did himself justice. He seldom spoke to Laurie, but he looked at him often, and a shadow would pass across his face, as if regretting his own lost youth, as he watched the young man in his prime. Then his eyes would turn to Jo so wistfully that she would have surely answered the mute inquiry if she had seen it. But Jo had her own eyes to ta ke care of, and feeling that the y could not be trusted, she prudently kept them on the little sock she was knitting, like a model maiden aunt. A stealthy glance now and then refreshed her like sips of fresh water after a dusty walk, for the sidelong peeps showed her several propitious omens. Mr. Bhaer39。s face had lost the absentminded expression, and looked all alive with interest in the present moment, actually y oung and handsome, she thought, fetting to pare him with Laurie, as she usually did strange men, to their great detrime nt. Then he seemed quite inspired, though the burial customs of the ancients, to which the conversation had strayed, might not be c onsidered an exhilarating topic. Jo quite glowed with triumph when Teddy got quenched in an argument, and thought to herself, as she watched her father39。s absorbed face, How he would enjoy having such a man as m y Professor to talk with every day! Lastly, Mr. Bhaer was dressed in a new suit of blac k, which made him look more like a gentleman than ever. His bushy hair had been cut and smoothly brushed, but didn39。t stay in order long, for in exciting moments, he rumpled it up in the droll way he used to do, and Jo liked it rampantly erect better than flat, because she thought it gave his fine forehead a Jove like aspect. Poor Jo, how she did glorify that plain man, as she sat knitting away so quietly, yet letting nothing escape her, not even the fact that Mr. Bhaer actually had gold sleevebuttons in his immaculate wristbands. Dear old fellow! He couldn39。t have got himself up with more care if he39。d been going a wooing, said Jo to herself, and then a sudden thought born of the w ords made her blush so dreadfully that she had to drop her ball, and go down after it to hide her face. The maneuver did not succeed as well as she expected, however, for though just in the act of sng creature39。 was let severely a lone, but Amy39。s talent and taste were duly plimented by the offer of the art table, and she exerted herself to prepare and secure appropriate and valuable contributions to it. Everything went on smoothly till the day before the fair opened, then there occurred one of the little skirmishes which it is almost impossible to avoid, when some fiveandtwenty women, old and young, with all their private piques and prejudices, try to work together. May Chester was rather jealous of Amy because the latter was a greater favorite than herself, and just at